This book describes the synthesis and characterization of niobium-based metal complexes and their usefulness as catalysts for the polymerization of ethylene, norbornene, beta pinene and vinyl monomers. The polymerization of above described monomers was studied using niobium complexes based on N,N dialkylcarbamates, mixed chloro alkoxides, simple oxygen-containing ligands and the starting material for the preparation of such derivatives, i.e. NbCl5.Niobium N,N-dialkylcarbamates exhibited high activity for polymerization of ethylene when activated with TMA-depleted MAO and 1,2-dichloroethane as...